Controlling the speed of motors.



No. 819,613. PATENTED MAY 1, 1906.

O. P. STEINMETZ. CONTROLLING THE SPEED OF MOTORS.

APPLICATION FILED SEPT. 26, 1902;

Witnesses. Inventor. 7 9/ Charles P. Steinmetz. MW by fitt'y.

UNITED STATES PATENT OFFICE.

CHARLES P. STEINMETZ, or soHENEorADY, NEW YORK. ASSIGNOR To GENERAL ELECTRIC COMPANY, A CORPORATION on NEW YORK.

CONTROLLING THE SPEED OF MOTORS.

' Specification of Letters Patent.-

Patented May 1, 1906.

Application filed September 26, 1902. Serial No. 124,897.

and its object is to enable the s eed of a multipolar motor tobe controlle within wide limits without the use of resistances in the circuit, which are wasteful-of current.

The invention is especially applicable to motors which drive'printing presses, which have to be started and stopped frequently and run at low speed while making ready the forms and starting in the paper or in taking roof impressions, but which must run at a 'gh speed when the press is at work. In order to render the motor capable of meeting such service demands, I provide its armature with two windings, preferably of different resistances, and arrange a switch to cut one or the other. into circuit, as desired. I also provide a 'rheostat for varying the field strength of the motor.

I prefer to use a multipolanmotor and to make one winding a multiple-circuit or parallel winding of the ordinary type and the other a two-circuit or series winding, preferably of finer wire and having a greater number of turns than the other. In an eight-pole motor, for example, if the series winding is of the same-sized wire and has no more turns than the main Winding it will give one-fourth the speed, while if it is only one-fourth the.- cross-section of the main wire and has four times as many turns it will give one-s11:- teenth the speed. Moreover, by varying the field strength a still greater regulation of speed can beobtained, or, if the three-wire system of supply is used, the motor can be connected at will to either side of the system,

and so halve the speed again.

The accompanying drawing is a diagram of I armature-windings and circuitconnections embodying my invention as appliedv to an eight-pole motor.

The shunt field-coils 1 are all, connected inseries with each other and with a rheostat 2,

.by means ofwhich the field strength can be "varied. The armature carries a main Winding 3 of the ordinary multiple-circuit 01' par v slot as the main winding 3. The two-circuitallel-wound type, having, preferably, only one 5 turn in each slot. The eight brushes 4 are connected in two sets of four each. The auxiliary two-circuit or series winding 5 haspreferably four turns to each coil laid in the same winding is connected with the commutator 6 in any of the approved series or two-circuit systems, the two brushes 7 being in proper position on the fcommutator. The series winding is preferably of smaller wire than the. main winding to give it higher resistance.

The brushes 4 7 are connected, respectively, I

with the stationary lower and u per contactclips 8 9 "of a double-pole ouble throw switch, whose movable blades 10' are connected with the terminals of the supply-leads 11.

To start the motor slowly, the switch is closed on..the contacts 9, thus energizin the vseries winding. By weakening the fie d of the motor the speed will increase up to, say, twice the original speed. This range is suf-. fioient for the operation of getting the press ready to work. To run rapidly, the switch is closed u on the contacts 8, cutting out the series win 111 and ener izing the parallel winding 3. yvarying t efield strength asbefore the speed due to the arallel winding can be considerablyincreased if desired.

If a three-wire system of distribution is used, a switch 12 may be rovidedto connect 8 the motor-leads with eit er side of the systern at will, and .thus get the variation in speed due to the diiference-in impressed electromotive force." Y

f By the terms parallel or multiple-circuit winding as used in the foregoin specificationand in the appended claims intend to designate the common type of winding, in 7 which a commutator-Se ment is connected to two adjacent coils, 'whi e by theterms se ries or two-circuit winding I mean the common type of winding in which a commutator-se ment is connected to' two coils dis: placed 50m each other on the armature by\ substantiall twice [the polar pitch.

What c aim as new, and desire to secure by Letters Patent of the United States, is-

1. The combination with a multipolar elec{ tric motor,- of means whereby the active armature-circuit maybe of. the parallel-wound or series-woundi'type, at, will, the number ofi poles of the motor remaining unchanged. I 2. A multipolar electric motor having two armature-windings, one multiple-circuit and the other two-circuit, and a switch for including either winding in circuit at will.

3. A Inultipolar electric motor having two an auxiliary series-wound winding of higher resistance than the main winding, and means for switching either winding into circuit,

In witness whereof I have hereunto set my armature-windings, one parallel and the other hand this 25th day of September, 1902.

series, means for switching either winding into circuit, and means for varying the held strength of the motor. 1

4. A multipolar electric motor having a 10 main parallel-wound armature-Winding, and

CHARLES P. STEINMET'J. Witnesses:

HELEN ORFoRD, N. O. MILLER. 

